Electrostatic application of powder material to solid dosage forms

Abstract

In a method of electrostatically applying a powder material to a solid dosage form, charged powder material is applied to a photoconductive drum ( 3 ), is transferred to an intermediate belt ( 4 ) and then to a solid dosage form ( 5 ). The belt ( 4 ) makes contact with the solid dosage form ( 5 ).

What is claimed is:  
     
       1. A method of electrostatically applying a powder material to a solid dosage form, the method comprising the steps of electrostatically applying a powder material to a first intermediate means, and transferring the powder material that has been applied to the first intermediate means from the first intermediate means to the solid dosage form, wherein there is contact between the first intermediate means and the solid dosage form on transfer of the powder material to the solid dosage form. 
     
     
       2. A method according to  claim 1 , wherein the powder material is applied to the first intermediate means by applying an electrostatic charge to the first intermediate means, and applying the powder material at a potential sufficiently different from the potential of the first intermediate means to cause the powder material to adhere to the first intermediate means. 
     
     
       3. A method according to  claim 2 , wherein the electrostatic charge is applied to the first intermediate means in a pattern. 
     
     
       4. A method according to  claim 2 , wherein the first intermediate means comprises a photo-conductive semi-conductor at its surface. 
     
     
       5. A method according to  claim 2 , wherein the powder material has an electrostatic charge opposite to the electrostatic charge on the first intermediate means. 
     
     
       6. A method according to  claim 5 , wherein the electrostatic charge on the powder material is applied by triboelectric charging or corona charging. 
     
     
       7. A method according to  claim 1 , wherein the first intermediate means conforms to the shape of the solid dosage form on transfer of the powder material to the solid dosage form. 
     
     
       8. A method according to  claim 1 , wherein the powder material that adheres to the first intermediate means is transferred from the first intermediate means to the solid dosage form by means of the contact between the first intermediate means and the solid dosage form. 
     
     
       9. A method according to  claim 1 , wherein the powder material that adheres to the first intermediate means is transferred from the first intermediate means to the solid dosage form by electrostatic means. 
     
     
       10. A method of electrostatically applying a powder material to a solid dosage form, the method comprising the steps of electrostatically applying a powder material to a first intermediate means, and transferring the powder material that has been applied to the first intermediate means from the first intermediate means to the solid dosage form, wherein the powder material that has been applied to the first intermediate means is transferred from the first intermediate means to the solid dosage form via a second intermediate means. 
     
     
       11. A method according to  claim 10 , wherein there is contact between the first intermediate means and the second intermediate means on transfer of the powder material from the first intermediate means to the second intermediate means. 
     
     
       12. A method according to  claim 10 , wherein there is contact between the second intermediate means and the solid dosage form on transfer of the powder material from the second intermediate means to the solid dosage form. 
     
     
       13. A method according to  claim 12 , wherein the second intermediate means conforms to the shape of the solid dosage form on transfer of the powder material to the solid dosage form. 
     
     
       14. A method according to  claim 1 , wherein the method further comprises the step of treating the powder material to fix it on the solid dosage form once it has been transferred to the solid dosage form. 
     
     
       15. A method according to  claim 1 , wherein the method further comprises the step of treating the powder material to fix it on the solid dosage form as it is being transferred to the solid dosage form. 
     
     
       16. A method according to  claim 14 , wherein the treatment of the powder material to secure it to the solid dosage form results in the formation of a continuous coating on the solid dosage form. 
     
     
       17. A method according to  claim 1 , which comprises the step of applying powder material to a first surface of the solid dosage form, and the subsequent step of applying powder material to a second surface of the solid dosage form. 
     
     
       18. A method according to  claim 1 , wherein the method is carried out as a continuous process. 
     
     
       19. A method according to  claim 1 , wherein the powder material includes a biologically active material. 
     
     
       20. A method according to  claim 1 , wherein the solid dosage form is a pharmaceutical solid dosage form. 
     
     
       21. A method according to  claim 20 , wherein the solid dosage form is for human use. 
     
     
       22. A method according to  claim 20 , wherein the solid dosage form is a pharmaceutical tablet. 
     
     
       23. An apparatus for electrostatically applying a powder material to a solid dosage form, the apparatus comprising means for applying a powder material to a first intermediate means, and means for transferring the powder material that has been applied to the first intermediate means from the first intermediate means to the solid dosage form, wherein the first intermediate means is positioned such that there is contact between the first intermediate means and the solid dosage form on transfer of the powder material to the solid dosage form. 
     
     
       24. An apparatus according to  claim 23 , wherein the first intermediate means comprises a photo-conductive semi-conductor. 
     
     
       25. An apparatus according to  claim 23 , wherein the first intermediate means is able to conform to the shape of the solid dosage form. 
     
     
       26. An apparatus for electrostatically applying a powder material to a solid dosage form, the apparatus comprising means for applying a powder material to a first intermediate means, and means for transferring the powder material that has been applied to the first intermediate means from the first intermediate means to the solid dosage form, wherein the apparatus further comprises means for transferring the powder material that has been applied to the first intermediate means to a second intermediate means, and means for transferring the powder material that has been transferred to the second intermediate means to the solid dosage form. 
     
     
       27. An apparatus according to  claim 26 , wherein the second intermediate means is positioned such that there is contact between the second intermediate means and the solid dosage form on transfer of the powder material to the solid dosage form. 
     
     
       28. An apparatus according to  claim 27 , wherein the second intermediate means is able to conform to the shape of the solid dosage form. 
     
     
       29. An apparatus according to  claim 23 , the apparatus further comprising means for treating the powder material to fix it on the solid dosage form once it has been transferred to the solid dosage form. 
     
     
       30. An apparatus according to  claim 23 , the apparatus further comprising means for treating the powder material to fix it on the solid dosage form as it is being transferred to the solid dosage form. 
     
     
       31. A coated substrate produced by a method according to  claim 1 . 
     
     
       32. An apparatus according to  claim 26 , wherein the first intermediate means comprises a photo-conductive semi-conductor.